1. Field of the Invention
The present invention relates generally to an apparatus for cutting predetermined lengths of a flexible material such as thread, rope, wire, tubing, and the like, and more specifically, to an apparatus for automatically cutting a predetermined length of suture material for attachment to a surgical needle. More particularly, the present invention relates to apparatus for cutting an indefinite length of suture to different discrete lengths for subsequent swaging to surgical needles, and having a tipping assembly. The tipping assembly heats a predetermined small length of the suture to stiffen it in preparation for cutting the stiffened suture at a cutting assembly and inserting a stiffened lead cut end of the suture into an end of a needle for swaging thereto. A long length of suture travel is provided between the tipping assembly and the cutter assembly which is a discrete number of apparatus cutting cycles between the tipping and cutting operations to allow the tipped suture to cool prior to cutting.
2. Description of the Prior Art
The medical products industry presently utilizes semi-automated procedures for swaging sutures to surgical needles. For instance, as described in U.S. Pat. No. 3,611,551, manual intervention is required by an operator to accurately position a suture within the needle for swaging and to adjust swaging dies to increase or decrease swage pressure when suture strands of different gauges are to be swaged. This process is costly in terms of man-hour labor and efficiency because manual positioning is required for swaging to take place.
Presently, suture material may be supplied wound on a bobbin, or, a king or driven spool before being cut and positioned within the swaging end of a surgical needle. In U.S. Pat. No. 3,980,177 the suture material is fed from a spool and taken up on a rotating tension rack where uniform length strands are subsequently cut. Thus, the length of the suture is determined by the size of the rack and manual intervention is required to change the rack each time a different length of suture is desired.
In U.S. Pat. No. 4,922,904, the suture material is supplied wound on a bobbin and is fed through various guide means and a heater for straightening the material, prior to insertion within the crimping cavity of the surgical needle. In one embodiment shown therein, an elaborate television monitoring means is required for aligning the drawn suture within the crimping cavity of the surgical needle prior to swaging thereof. In the same embodiment, a rotary encoder device is used to determine the length of suture material unwound from the bobbin prior to cutting. In an alternative embodiment, after swaging of the indefinite length of suture material to the needle, the needle-suture assembly is additionally fed a predetermined distance prior to cutting to obtain a suture strand of predetermined length. Thus, to obtain uniform lengths of suture material every time requires careful manipulations and precise controls, and the processes used to accomplish these tasks are also costly in terms of man-hour labor and efficiency.
It would be far more desirable to provide a suture cutting system and apparatus that is fully automated and which can automatically cut uniform lengths of suture material at high-speeds.
It would also be highly desirable to provide a suture cutting system that can accurately position suture material within the confines of the crimping ends of surgical needles at an appreciable rate and without elaborate techniques or manual procedures.
It would also be desirable to provide a suture cutting system which is operable under the control of a control system computer, and which can provide automatic adjustments to the swage tooling dies when different size sutures are swaged into various sized surgical needles.
Accordingly, it is an object of the instant invention to provide an automatic suture cutting assembly that virtually eliminates operator exposure to repetitive manual operations.
Another object of the instant invention is to provide a suture cutting apparatus that is fully automated and which can automatically and cleanly cut uniform lengths of suture material at high-speeds and without brooming of the suture tip.
It is another object of the instant invention to provide a suture cutting apparatus that includes a heat treating (tipping) device for stiffening a portion of the suture strand to be cut to aid in its insertion within a suture receiving end of a surgical needle.
Still another object of the instant invention is to provide a cutting apparatus which can be automatically set up to cut predetermined lengths of flexible articles or strands.
Yet another object of the present invention is to provide a suture cutting system that can accurately position suture material within the confines of a suture receiving opening of a surgical needle at an appreciable rate and without manual intervention.
These and other objects of the present invention are attained with an apparatus for cutting an indefinite length suture strand to uniform lengths for subsequent threading and swaging to a surgical needle having a suture receiving opening formed therein, wherein the apparatus comprises a drawing frame having at least one longitudinal member and defining a drawing axis parallel thereto. A means for feeding the indefinite length suture strand to the drawing axis for drawing and cutting thereof is provided. First and second gripping means are provided for gripping the indefinite length suture strand and drawing it along the drawing axis; the first gripping means being mounted for reciprocal movement on the longitudinal member. Also provided is a retractable cutting means for cutting the indefinite length suture strand to obtain a clean and broom-free horizontal cut. The second gripping means reciprocates to a start position along the drawing axis while the first gripping means is drawing the indefinite length suture strand to a predetermined distance beyond the retractable cutting means. The indefinite length suture strand is then inserted within the suture receiving opening of the needle and cut to a predetermined length by the retractable cutting means after the second gripping means has gripped the indefinite length suture strand at the start position.
Another object of the present invention is to provide an apparatus for cutting an indefinite length of suture to different lengths for subsequent swaging to surgical needles, and having a tipping assembly. The tipping assembly heats a predetermined small length of the suture to stiffen it in preparation for cutting the stiffened suture at a cutting assembly and inserting a stiffened lead cut end of the suture into an end of a needle for swaging thereto. A long length of suture travel is provided between the tipping assembly and the cutter assembly which is a discrete number of apparatus cutting cycles between the tipping and cutting operations to allow the tipped suture to cool prior to cutting.
In accordance with a preferred embodiment, the present invention provides an apparatus for cutting an indefinite length of suture to uniform lengths for subsequent threading and swaging to surgical needles having a suture receiving opening formed therein. The apparatus comprises a drawing frame, having at least one longitudinal member and defining a drawing axis parallel thereto. A tipping assembly is provided for heating a predetermined small length of the suture to stiffen the small length of suture after subsequent cooling thereof, in preparation for cutting the suture at the stiffened small length and inserting a stiffened lead cut end of the suture into an end of a needle for swaging thereto. First and second grippers are provided for gripping the indefinite length suture and alternately drawing it along the drawing axis. The first and second grippers are mounted for reciprocal movement on the longitudinal member(s). In operation one of the first and second grippers draws the indefinite length suture to a position beyond a cutter assembly, while the other of the first and second grippers reciprocates to a start position along the drawing axis before the cutting, assembly, such that the first and second grippers are used alternately to draw suture through the apparatus and feed the suture into a needle. The cutting assembly severs the indefinite length suture to provide uniform lengths of suture. In accordance with the present invention, a predetermined long length of suture travel is provided between the tipping assembly and the cutter assembly, wherein the predetermined long length of suture travel is a discrete number, two or more, times the uniform length of suture being cut by the apparatus. This provides a discrete number, two or more, of apparatus cutting cycles between tipping of the suture at the tipping assembly and cutting of the suture at the cutting assembly, such that after heating of a small length of suture at the tipping assembly, the suture is cooled to allow setting and hardening of the suture material prior to cutting.
In greater detail, the discrete number of uniform length of suture or apparatus cutting cycles comprises at least three. At least one small diameter idler roller is provided for guiding the suture to the tipping assembly, and after heating thereat, the suture is drawn to and rotates around a large diameter idler roller. The larger diameter of the idler roller is provided because the small length of suture which has been heated at the tipping assembly has begun to harden and set by the time the heated suture reaches the large diameter idler roller. The large diameter thereof facilitates the suture to travel therearound and change direction without picking up a permanent curved set from the large idler roller, to provide a straight suture, without any curve, when it is subsequently cut and inserted into a needle. The large diameter idler roller has a diameter larger than 6 inches, and in one embodiment is 7 inches. The tipping assembly is positioned near the top of the apparatus, and the large diameter idler roller is positioned near the bottom of the apparatus, and the suture reverses direction at the large diameter roller and is drawn vertically upwardly to the first and second grippers and the cutter assembly.
The position of the cutting assembly along the drawing axis is continuously adjustable to provide an infinite number of possible different lengths of cut suture. For each different position of the cutting assembly, the tipping assembly is adjustably positioned at a different predetermined position in the apparatus to provide for the tipped section of suture to be precisely positioned at the cutter assembly after a discrete number of apparatus cycles. The tipping assembly includes a pointer positioned adjacent to a linear measurement scale stationarily positioned in the apparatus, such that the position of the tipping assembly is precisely controlled by aligning the pointer with a specified reading on the linear measurement scale. The position of the tipping assembly in the apparatus is adjustable by rotation of a handcrank and precision leadscrew.
The suture is initially drawn into the apparatus, and extends to and is wrapped around a tension roller which is mounted on one end of a torque motor, which applies a given tension to the suture as it is pulled through the apparatus by the first and second grippers. The suture is wrapped around the tension roller a multiple number of times, in one embodiment twice. Each different suture size and material has a different tension applied thereto by the torque motor as it is drawn through the apparatus, and the specific tension force is downloaded from a computer program at each suture batch changeover. Moreover, each of the first and second grippers includes a releasable suture clamp positioned thereon which releasably clamps the suture during an initial auto threading of a new lead of suture through the apparatus.